Multiple precursor concentric delivery showerhead

ABSTRACT

A method and apparatus that may be utilized for chemical vapor deposition and/or hydride vapor phase epitaxial (HVPE) deposition are provided. In one embodiment, the apparatus provides a processing chamber that includes a showerhead with separate inlets and channels for delivering separate processing gases into a processing volume of the chamber without mixing the gases prior to entering the processing volume. In one embodiment, a plurality of concentric tube assemblies are disposed within the showerhead to separately deliver a first gas from a first gas channel and a second gas from a second gas channel into the processing volume of the chamber. In one embodiment, the showerhead further includes a heat exchanging channel through which the plurality of concentric tube assemblies is disposed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit of U.S. Provisional Patent ApplicationSer. No. 61/324,271 (APPM/015324L), filed Apr. 14, 2010, which is hereinincorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Embodiments of the present invention generally relate to methods andapparatus for chemical vapor deposition (CVD) on a substrate, and, inparticular, to a showerhead design for use in metal organic chemicalvapor deposition (MOCVD) and/or hydride vapor phase epitaxy (HVPE).

2. Description of the Related Art

Group III-V films are finding greater importance in the development andfabrication of a variety of semiconductor devices, such as shortwavelength light emitting diodes (LEDs), laser diodes (LDs), andelectronic devices including high power, high frequency, hightemperature transistors and integrated circuits. For example, shortwavelength (e.g., blue/green to ultraviolet) LEDs are fabricated usingthe Group III-nitride semiconducting material gallium nitride (GaN). Ithas been observed that short wavelength LEDs fabricated using GaN canprovide significantly greater efficiencies and longer operatinglifetimes than short wavelength LEDs fabricated using non-nitridesemiconducting materials, such as Group II-VI materials.

One method that has been used for depositing Group III-nitrides, such asGaN, is metal organic chemical vapor deposition (MOCVD). This chemicalvapor deposition method is generally performed in a reactor having atemperature controlled environment to assure the stability of a firstprecursor gas which contains at least one element from Group III, suchas gallium (Ga). A second precursor gas, such as ammonia (NH₃), providesthe nitrogen needed to form a Group III-nitride. The two precursor gasesare injected into a processing zone within the reactor where they mixand move towards a heated substrate in the processing zone. A carriergas may be used to assist in the transport of the precursor gasestowards the substrate. The precursors react at the surface of the heatedsubstrate to form a Group III-nitride layer, such as GaN, on thesubstrate surface. The quality of the film depends in part upondeposition uniformity which, in turn, depends upon uniform mixing of theprecursors across the substrate.

Multiple substrates may be arranged on a substrate carrier and eachsubstrate may have a diameter ranging from 50 mm to 100 mm or larger.The uniform mixing of precursors over larger substrates and/or moresubstrates and larger deposition areas is desirable in order to increaseyield and throughput. These factors are important since they directlyaffect the cost to produce an electronic device and, thus, a devicemanufacturer's competitiveness in the marketplace.

Interaction of the precursor gases with the hot hardware components,which are often found in the processing zone of an LED or LD formingreactor, generally causes the precursor to break-down and deposit onthese hot surfaces. Typically, the hot reactor surfaces are formed byradiation from the heat sources used to heat the substrates. Thedeposition of the precursor materials on the hot surfaces can beespecially problematic when it occurs in or on the precursordistribution components, such as the showerhead. Deposition on theprecursor distribution components affects the flow distributionuniformity over time. Therefore, there is a need for a gas distributionapparatus that prevents or reduces the likelihood that the MOCVDprecursors, or HVPE precursors, are heated to a temperature that causesthem to break down and affect the performance of the gas distributiondevice.

Also, as the demand for LEDs, LDs, transistors, and integrated circuitsincreases, the efficiency of depositing high quality Group-III nitridefilms takes on greater importance. Therefore, there is a need for animproved deposition apparatus and process that can provide consistentfilm quality over larger substrates and larger deposition areas.

SUMMARY OF THE INVENTION

The present invention generally provides improved methods and apparatusfor depositing Group III-nitride films using MOCVD and/or HVPEprocesses.

One embodiment of the present invention provides a showerhead apparatuscomprising a first gas channel coupled to a first gas inlet, a secondgas channel coupled to a second gas inlet, a plurality of first gasconduits fluidly coupling the first gas channel to an exit surface ofthe showerhead apparatus, and a plurality of second gas conduits fluidlycoupling the second gas channel to the exit surface of the showerheadapparatus. The first gas channel is isolated from the second gaschannel, and at least one of the first gas conduits is disposed withinat least one of the second gas conduits.

Another embodiment provides a substrate processing apparatus comprisinga chamber body, a substrate support, and a showerhead apparatus, whereina processing volume is defined by the chamber body, the substratesupport, and the showerhead apparatus. The showerhead apparatuscomprises a first gas channel coupled to a first gas inlet, a second gaschannel coupled to a second gas inlet, a plurality of first gas conduitsfluidly coupling the first gas channel to the processing volume, and aplurality of second gas conduits fluidly coupling the second gas channelto the processing volume. The first gas channel is isolated from thesecond gas channel, and at least one of the first gas conduits isconcentrically disposed within at least one of the second gas conduits.

Yet another embodiment of the present invention provides a method ofprocessing substrates comprising introducing a first gas into aprocessing volume of a processing chamber through a first gas inletcoupled to a first gas channel of a showerhead assembly and introducinga second gas into the processing volume of the processing chamberthrough a second gas inlet coupled to a second gas channel of theshowerhead assembly. The first gas channel is isolated from the secondgas channel, and the first gas is delivered into the processing volumethrough a plurality of first gas conduits and the second gas isdelivered into the processing volume through a plurality of second gasconduits. At least one of the first gas conduits is concentricallydisposed within at least one of the second gas conduits.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentinvention can be understood in detail, a more particular description ofthe invention, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

FIG. 1 is a schematic plan view illustrating one embodiment of aprocessing system for fabricating compound nitride semiconductor devicesaccording to embodiments described herein.

FIG. 2 is a schematic cross-sectional view of a metal-organic chemicalvapor deposition (MOCVD) chamber for fabricating compound nitridesemiconductor devices according to one embodiment of the presentinvention.

FIG. 3 is an enlarged view of detail A shown in FIG. 2.

FIG. 4A is a partial, schematic, bottom view of a multiple precursorshowerhead showing a classic, one-to-one, square pattern of gaspassages.

FIG. 4B is a partial, schematic, bottom view of the showerhead from FIG.2 and according to one embodiment of the present invention.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is contemplated that elements and features of oneembodiment may be beneficially incorporated in other embodiments withoutfurther recitation.

DETAILED DESCRIPTION

Embodiments of the present invention generally provide a method andapparatus that may be utilized for deposition of Group III-nitride filmsusing MOCVD and/or HVPE hardware. In one embodiment, the apparatus aprocessing chamber that includes a showerhead with separate inlets andchannels for delivering separate processing gases into a processingvolume of the chamber without mixing the gases prior to entering theprocessing volume. In one embodiment, a plurality of concentric tubeassemblies are disposed within the showerhead to separately deliver afirst gas from a first gas channel and a second gas from a second gaschannel into the processing volume of the chamber. In one embodiment,the showerhead further includes a cooling channel through which theplurality of concentric tube assemblies is disposed.

FIG. 1 is a schematic plan view illustrating one embodiment of aprocessing system 100 that comprises the one or more MOCVD chambers 102for fabricating compound nitride semiconductor devices according toembodiments described herein. In one embodiment, the processing system100 is closed to atmosphere. The processing system 100 comprises atransfer chamber 106, a MOCVD chamber 102 coupled with the transferchamber 106, a loadlock chamber 108 coupled with the transfer chamber106, a batch loadlock chamber 109, for storing substrates, coupled withthe transfer chamber 106, and a load station 110, for loadingsubstrates, coupled with the loadlock chamber 108. The transfer chamber106 comprises a robot assembly (not shown) operable to pick up andtransfer substrates between the loadlock chamber 108, the batch loadlockchamber 109, and the MOCVD chamber 102. Although a single MOCVD chamber102 is shown, it should be understood that more than one MOCVD chamber102 or additionally, combinations of one or more MOCVD chambers 102 withone or more Hydride Vapor Phase Epitaxial (HVPE) chambers may also becoupled with the transfer chamber 106. It should also be understood thatalthough a cluster tool is shown, the embodiments described herein maybe performed using linear track systems.

In one embodiment, the transfer chamber 106 remains under vacuum duringsubstrate transfer processes. The transfer chamber vacuum level may beadjusted to match the vacuum level of the MOCVD chamber 102. Forexample, when transferring substrates from a transfer chamber 106 intothe MOCVD chamber 102 (or vice versa), the transfer chamber 106 and theMOCVD chamber 102 may be maintained at the same vacuum level. Then, whentransferring substrates from the transfer chamber 106 to the load lockchamber 108 (or vice versa) or the batch load lock chamber 109 (or viceversa), the transfer chamber vacuum level may be adjusted to match thevacuum level of the loadlock chamber 108 or batch load lock chamber 109even through the vacuum level of the loadlock chamber 108 or batch loadlock chamber 109 and the MOCVD chamber 102 may be different. Thus, thevacuum level of the transfer chamber 106 is adjustable. In certainembodiments, substrates are transferred in a high purity inert gasenvironment, such as, a high purity N₂ environment. In one embodiment,substrates transferred in an environment having greater than 90% N₂. Incertain embodiments, substrates are transferred in a high purity NH₃environment. In one embodiment, substrates are transferred in anenvironment having greater than 90% NH₃. In certain embodiments,substrates are transferred in a high purity H₂ environment. In oneembodiment, substrates are transferred in an environment having greaterthan 90% H₂.

In the processing system 100, the robot assembly (not shown) transfers asubstrate carrier plate 112 loaded with substrates into the single MOCVDchamber 102 to undergo deposition. In one embodiment, the substratecarrier plate 112 may have a diameter ranging from about 200 mm to about750 mm. The substrate carrier plate 112 may be formed from a variety ofmaterials, including SiC or SiC-coated graphite. In one embodiment, thesubstrate carrier plate 112 comprises a silicon carbide material. In oneembodiment, the substrate carrier plate 112 has a surface area of about1,000 cm² or more, preferably 2,000 cm² or more, and more preferably4,000 cm² or more. After some or all deposition steps have beencompleted, the substrate carrier plate 112 is transferred from the MOCVDchamber 102 back to the loadlock chamber 108 via the transfer robot. Inone embodiment, the substrate carrier plate 112 is then transferred tothe load station 110. In another embodiment, the substrate carrier plate112 may be stored in either the loadlock chamber 108 or the batch loadlock chamber 109 prior to further processing in the MOCVD chamber 102.One exemplary processing system 100 that may be adapted in accordancewith embodiments of the present invention is described in U.S. patentapplication Ser. No. 12/023,572, filed Jan. 31, 2008, now published asUS 2009-0194026, entitled PROCESSING SYSTEM FOR FABRICATING COMPOUNDNITRIDE SEMICONDUCTOR DEVICES, which is hereby incorporated by referencein its entirety.

In one embodiment, a system controller 160 controls activities andoperating parameters of the processing system 100. The system controller160 includes a computer processor and a computer-readable memory coupledto the processor. The processor executes system control software, suchas a computer program stored in memory. Exemplary aspects of theprocessing system 100 and methods of use adaptable to embodiments of thepresent invention are further described in U.S. patent application Ser.No. 11/404,516, filed Apr. 14, 2006, now published as US 2007-024516,entitled EPITAXIAL GROWTH OF COMPOUND NITRIDE STRUCTURES, which ishereby incorporated by reference in its entirety.

FIG. 2 is a schematic cross-sectional view of the MOCVD chamber 102according to embodiments of the present invention. The MOCVD chamber 102comprises a chamber body 202, a chemical delivery module 203 fordelivering precursor gases, carrier gases, cleaning gases, and/or purgegases, a remote plasma system 226 with a plasma source, a susceptor orsubstrate support 214, and a vacuum system 212. The chamber body 202encloses a processing volume 208. A showerhead assembly 204 is disposedat one end of the processing volume 208, and the substrate carrier plate112 is disposed at the other end of the processing volume 208. Thesubstrate carrier plate 112 may be disposed on the substrate support214. The substrate support 214 has z-lift capability for moving in avertical direction, as shown by arrow 215. In one embodiment, the z-liftcapability may be used to move the substrate support 214 upwardly, andcloser to the showerhead assembly 204, and downwardly, and further awayfrom the showerhead assembly 204. In one embodiment, the distance fromthe surface of the showerhead assembly 204 that is adjacent theprocessing volume 208 to the substrate carrier plate 112 duringprocessing ranges from about 4 mm to about 41 mm. In certainembodiments, the substrate support 214 comprises a heating element(e.g., a resistive heating element (not shown)) for controlling thetemperature of the substrate support 214 and consequently controllingthe temperature of the substrate carrier plate 112 and substrates 240positioned on the substrate carrier plate 112 and the substrate support214.

In one embodiment, the showerhead assembly 204 has a first processinggas channel 204A coupled with the chemical delivery module 203 via afirst processing gas inlet 259 for delivering a first precursor or firstprocess gas mixture to the processing volume 208. In one embodiment, thechemical delivery module 203 is configured to deliver a metal organicprecursor to the first processing gas channel 204A. In one example, themetal organic precursor comprises a suitable gallium (Ga) precursor(e.g., trimethyl gallium (“TMG”), triethyl gallium (TEG)), a suitablealuminum precursor (e.g., trimethyl aluminum (“TMA”)), or a suitableindium precursor (e.g., trimethyl indium (“TMI”)).

In one embodiment, a blocker plate 255 is positioned across the firstprocessing gas channel 204A. The blocker plate 255 has a plurality oforifices 257 disposed therethrough. In one embodiment, the blocker plate255 is positioned between the first processing gas inlet 259 and thefirst processing gas channel 204A for uniformly distributing gasreceived from the chemical delivery module 203 into the first processinggas channel 204A.

In one embodiment, the showerhead assembly 204 has a second processinggas channel 204B coupled with the chemical delivery module 203 fordelivering a second precursor or second process gas mixture to theprocessing volume 208 via a second processing gas inlet 258. In oneembodiment, the chemical delivery module 203 is configured to deliver asuitable nitrogen containing processing gas, such as ammonia (NH₃) orother MOCVD or HVPE processing gas, to the second processing gas channel204B. In one embodiment, the second processing gas channel 204B isseparated from the first processing gas channel 204A by a firsthorizontal wall 276 of the showerhead 204.

The showerhead assembly 204 may further include a temperature controlchannel 204C coupled with a heat exchanging system 270 for flowing aheat exchanging fluid through the showerhead assembly 204 to helpregulate the temperature of the showerhead assembly 204. Suitable heatexchanging fluids include, but are not limited to, water, water-basedethylene glycol mixtures, a perfluoropolyether (e.g., Galden® fluid),oil-based thermal transfer fluids, or similar fluids. In one embodiment,the second processing gas channel 204B is separated from the temperaturecontrol channel 204C by a second horizontal wall 277 of the showerhead204. The temperature control channel 204C may be separated from theprocessing volume 208 by a third horizontal wall 278 of the showerhead204.

FIG. 3 is an enlarged view of detail A shown in FIG. 2. Referring toFIGS. 2 and 3, in one embodiment, the first precursor or firstprocessing gas mixture, such as a metal organic precursor, is deliveredfrom the first processing gas channel 204A through the second processinggas channel 204B and the temperature control channel 204C into theprocessing volume 208 via a plurality of inner gas conduits 246. Theinner gas conduits 246 may be cylindrical tubes located within alignedholes disposed through the first horizontal wall 276, the secondhorizontal wall 277, and the third horizontal wall 278 of the showerhead204. In one embodiment, the inner gas conduits 246 are each attached tothe first horizontal wall 276 of the showerhead assembly 204 by suitablemeans, such as brazing.

In one embodiment, the second precursor or second processing gasmixture, such as a nitrogen precursor, is delivered from the secondprocessing gas channel 204B through the temperature control channel 204Cand into the processing volume 208 via a plurality of outer gas conduits245. The outer gas conduits 245 may be cylindrical tubes each locatedconcentrically about a respective inner gas conduit 246. The outer gasconduits 245 are located within the aligned holes disposed through thesecond horizontal wall 277 and the third horizontal wall 278 of theshowerhead 204. In one embodiment, the outer gas conduits 245 are eachattached to the second horizontal wall 277 of the showerhead assembly204 by suitable means, such as brazing.

As previously presented, the MOCVD chamber 102 may be used fordeposition of Group III-nitride films. In one embodiment, the GroupIII-nitride films are deposited at a temperature exceeding about 550° C.In one embodiment, during processing, a cooling fluid is circulatedthrough the temperature control channel 204C in order to cool theshowerhead assembly 204, and in particular, to cool the metal organicprecursor being delivered through the inner gas conduits 246, whichextend through the cooling channel 204C, to prevent decomposition of themetal organic precursor before it is introduced into the processingvolume 208. Additionally, it is believed that surrounding the metalorganic precursor flowing through each inner gas conduit 246 with a flowof nitrogen-containing gas through the second processing gas channel204B and each outer conduit 245, provides additional cooling and thermalinsulation from the high processing temperatures within the processingvolume 208, in order to prevent decomposition of the metal organicprecursor before it is introduced into the processing volume 208.

FIG. 4A is a partial, schematic, bottom view of a multiple precursorshowerhead 400 having a classic, one-to-one, square pattern of gaspassages. Similar to embodiments of the present invention, theshowerhead 400 has a first processing gas channel coupled to aprocessing region via a first gas conduit 402 and a second processinggas channel coupled to the processing region via a second gas conduit404. In the depicted configuration, the first conduits 402 and thesecond gas conduits 404 are configured in a one-to-one square pattern.The configuration depicted in FIG. 4A results in a pattern in which eachrow of conduits has more of the second gas conduits 404 than the firstgas conduits 402 or vice versa. Additionally, the one-to-one squarepattern of first and second gas conduits (402 and 404) results in alimited number of gas passages from each gas channel due to spaceconstraints. The result is a less uniform than desirable distribution ofgases across substrates positioned in the processing volume, resultingin less than desirable deposition uniformity.

FIG. 4B is a partial, schematic, bottom view of the showerhead assembly204 from FIG. 2 and according to one embodiment of the presentinvention. As depicted, the concentric tube configuration comprising theouter gas conduit 245 that delivers a second gas from the secondprocessing gas channel 204B and the inner gas conduit 246 that deliversa first gas from the first processing gas channel 204A are arranged in amuch closer and more uniform pattern as compared to that shown in FIG.4A. In one embodiment, the concentric tubes are configured in ahexagonal close packed arrangement. Such a configuration provides asignificantly increased number of gas passages for both the first andsecond processing gases as compared to the configuration depicted inFIG. 4A. For instance, the configuration depicted in FIG. 4B has overtwice as many gas passages for each processing gas as the configurationdepicted in FIG. 4A for showerheads (204, 400) having the same surfacearea exposed to the processing volume 208. As a result of theconfiguration depicted in FIG. 4B, each of the first and secondprocessing gases, delivered from the first processing gas channel 204Aand the second processing gas channel 204B, is delivered more evenlyacross the substrates 240 positioned in the processing volume 208,resulting in significantly more deposition uniformity than theconfiguration depicted in FIG. 4A.

Exemplary showerheads that may be adapted to practice embodimentsdescribed herein are described in U.S. patent application Ser. No.11/873,132, filed Oct. 16, 2007, now published as US 2009-0098276,entitled MULTI-GAS STRAIGHT CHANNEL SHOWERHEAD, U.S. patent applicationSer. No. 11/873,141, filed Oct. 16, 2007, now published as US2009-0095222, entitled MULTI-GAS SPIRAL CHANNEL SHOWERHEAD, and U.S.patent application Ser. No. 11/873,170, filed Oct. 16, 2007, nowpublished as US 2009-0095221, entitled MULTI-GAS CONCENTRIC INJECTIONSHOWERHEAD, all of which are incorporated by reference in theirentireties.

Referring back to FIG. 2, a lower dome 219 is disposed at one end of alower volume 210, and the substrate carrier plate 112 is disposed at theother end of the lower volume 210. The substrate carrier plate 112 isshown in an elevated, process position, but may be moved to a lowerposition where, for example, the substrates 240 may be loaded orunloaded. An exhaust ring 220 may be disposed around the periphery ofthe substrate carrier plate 112 to help prevent deposition fromoccurring in the lower volume 210 and also help direct exhaust gasesfrom the chamber 102 to exhaust ports 209. The lower dome 219 may bemade of transparent material, such as high-purity quartz, to allow lightto pass through for radiant heating of the substrates 240. The radiantheating may be provided by a plurality of inner lamps 221A and outerlamps 221B disposed below the lower dome 219. Reflectors 266 may be usedto help control exposure of the chamber 102 to the radiant energyprovided by the inner and outer lamps 221A, 221B. Additional rings oflamps (not shown) may also be used for finer temperature control of thesubstrates 240.

In certain embodiments of the present invention, a purge gas (e.g., anitrogen containing gas) is delivered into the chamber 102 from theshowerhead assembly 204 through one or more purge gas channels 281coupled to a purge gas source 282. In this embodiment, the purge gas isdistributed through a plurality of orifices 284 about the periphery ofthe showerhead 204. The plurality of orifices 284 may be configured in acircular pattern about the periphery of the showerhead assembly 204 andpositioned distribute the purge gas about the periphery of the substratecarrier plate 112 to prevent undesirable deposition on edges of thesubstrate carrier plate 112, the showerhead 204, and other components ofthe chamber 102, which result in particle formation and, ultimatelycontamination of the substrates 240. The purge gas flows downwardly intomultiple exhaust ports 209, which are disposed around an annular exhaustchannel 205. An exhaust conduit 206 connects the annular exhaust channel205 to a vacuum system 212, which includes a vacuum pump 207. Thepressure of the chamber 102 may be controlled using a valve system,which controls the rate at which the exhaust gases are drawn from theannular exhaust channel 205.

In other embodiments, purge gas tubes 283 are disposed near the bottomof the chamber body 102. In this configuration, the purge gas enters thelower volume 210 of the chamber 102 and flows upwardly past thesubstrate carrier plate 112 and exhaust ring 220 and into the multipleexhaust ports 209. Other aspects of the MOCVD chamber 102 are describedin U.S. patent application Ser. No. 12/023,520, filed Jan. 31, 2008,published as US 2009-0194024, and titled CVD APPARATUS, which is hereinincorporated by reference in its entirety.

The chemical delivery module 203 supplies chemicals to the MOCVD chamber102. Reactive gases (e.g., first and second precursor gases), carriergases, purge gases, and cleaning gases may be supplied from the chemicaldelivery system through supply lines and into the chamber 102. In oneembodiment, the gases are supplied through supply lines and into a gasmixing box where they are mixed together and delivered to the showerheadassembly 204. Generally supply lines for each of the gases includeshut-off valves that can be used to automatically or manually shut-offthe flow of the gas into its associated line, and mass flow controllersor other types of controllers that measure the flow of gas or liquidthrough the supply lines. Supply lines for each of the gases may alsoinclude concentration monitors for monitoring precursor concentrationsand providing real time feedback. Backpressure regulators may beincluded to control precursor gas concentrations. Valve switchingcontrol may be used for quick and accurate valve switching capability.Moisture sensors in the gas lines measure water levels and can providefeedback to the system software which in turn can providewarnings/alerts to operators. The gas lines may also be heated toprevent precursors and cleaning gases from condensing in the supplylines. Depending upon the process used some of the sources may be liquidrather than gas. When liquid sources are used, the chemical deliverymodule includes a liquid injection system or other appropriate mechanism(e.g., a bubbler) to vaporize the liquid. Vapor from the liquids is thenusually mixed with a carrier gas as would be understood by a person ofskill in the art.

The remote plasma system 226 can produce a plasma for selectedapplications, such as chamber cleaning or etching residue from a processsubstrate. Plasma species produced in the remote plasma system 226 fromprecursors supplied via an input line are sent via a conduit 204D fordispersion through the showerhead assembly 204 to the MOCVD chamber 102.Precursor gases for a cleaning application may include chlorinecontaining gases, fluorine containing gases, iodine containing gases,bromine containing gases, nitrogen containing gases, and/or otherreactive elements. The remote plasma system 226 may also be adapted todeposit CVD layers flowing appropriate deposition precursor gases intoremote plasma system 226 during a layer deposition process. In oneembodiment, the remote plasma system 226 is used to deliver activechlorine species to the processing volume 208 for cleaning the interiorof the MOCVD chamber 102.

The temperature of the walls of the MOCVD chamber 102 and surroundingstructures, such as the exhaust passageway, may be further controlled bycirculating a heat-exchange liquid through channels (not shown) in thewalls of the chamber 102. The heat-exchange liquid can be used to heator cool the chamber body 202 depending on the desired effect. Forexample, hot liquid may help maintain an even thermal gradient during athermal deposition process, whereas a cool liquid may be used to removeheat from the system during an in-situ plasma process, or to limitformation of deposition products on the walls of the chamber. Thisheating, referred to as heating by the “heat exchanger”, beneficiallyreduces or eliminates condensation of undesirable reactant products andimproves the elimination of volatile products of the process gases andother contaminants that might contaminate the process if they were tocondense on the walls of cool vacuum passages and migrate back into theprocessing chamber during periods of no gas flow.

In one embodiment, during processing, a first precursor gas flows fromthe first processing gas channel 204A in the showerhead assembly 204 anda second precursor gas flows from the second processing gas channel 204Bformed in the showerhead assembly 204 towards the surface of thesubstrates 240. As noted above, the first precursor gas and/or secondprecursor gas may comprise one or more precursor gases or process gassesas well as carrier gases and dopant gases which may be mixed with theprecursor gases. The draw of the exhaust ports 209 may affect gas flowso that the process gases flow substantially tangential to thesubstrates 240 and may be uniformly distributed radially across thesubstrate deposition surfaces in a laminar flow. In one embodiment, theprocessing volume 208 may be maintained at a pressure of about 760 Torrdown to about 80 Torr.

In summary, embodiments of the present invention include a showerheadassembly having concentric tube assemblies for separately deliveringprocessing gases into a processing volume of a processing chamber. Theconcentric tube assemblies may be disposed in a hexagonal close packedarrangement for providing greater uniformity of the processing gasesinto the processing volume of the processing chamber. As a result,improved deposition uniformity is achieved on a plurality of substratespositioned in the processing volume of the processing chamber.

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

1. A showerhead apparatus, comprising: a first gas channel coupled to afirst gas inlet; a second gas channel coupled to a second gas inlet,wherein the first gas channel is isolated from the second gas channel; atemperature control channel coupled to a heat exchanging systemconfigured to supply a heat exchanging fluid through the temperaturecontrol channel; a plurality of first gas conduits extending through thetemperature control channel and fluidly coupling the first gas channelto an exit surface of the showerhead apparatus; and a plurality ofsecond gas conduits extending through the temperature control channeland fluidly coupling the second gas channel to the exit surface of theshowerhead apparatus, wherein at least one of the first gas conduits isdisposed within at least one of the second gas conduits.
 2. Theapparatus of claim 1, wherein each of the first and second gas conduitsforms a concentric tube assembly.
 3. The apparatus of claim 2, whereinthe concentric tube assemblies are configured in a hexagonal closepacked arrangement.
 4. The apparatus of claim 3, wherein the first gaschannel is disposed above the second gas channel.
 5. The apparatus ofclaim 4, wherein the second gas channel is disposed above thetemperature control channel.
 6. The apparatus of claim 2, furthercomprising a blocker plate positioned between the first gas inlet andthe first gas channel.
 7. The apparatus of claim 2, wherein theshowerhead apparatus has a plurality of gas passages disposed about theperiphery of the exit surface, wherein the plurality of gas passages arefluidly coupled to a purge gas inlet, and wherein the plurality of gaspassages are isolated from the first gas channel, the second gaschannel, and the temperature control.
 8. The apparatus of claim 2,wherein the first gas inlet is coupled to a metal organic gas source,and wherein the second gas inlet is coupled to a nitrogen containing gassource.
 9. A substrate processing apparatus, comprising: a chamber body;a substrate support; and a showerhead apparatus, wherein a processingvolume is defined by the chamber body, the substrate support, and theshowerhead apparatus, and wherein the showerhead apparatus comprises: afirst gas channel coupled to a first gas inlet; a second gas channelcoupled to a second gas inlet, wherein the first gas channel is isolatedfrom the second gas channel; a temperature control channel coupled to aheat exchanging system configured to supply a heat exchanging fluidthrough the temperature control channel; a plurality of first gasconduits extending through the temperature control channel and fluidlycoupling the first gas channel to the processing volume; and a pluralityof second gas conduits extending through the temperature control channeland fluidly coupling the second gas channel to the processing volume,wherein at least one of the first gas conduits is concentricallydisposed within at least one of the second gas conduits.
 10. Theapparatus of claim 9, wherein each of the first and second gas conduitsforms a concentric tube assembly.
 11. The apparatus of claim 10, whereinthe concentric tube assemblies are configured in a hexagonal closepacked arrangement.
 12. The apparatus of claim 9, wherein the showerheadfurther comprises a blocker plate disposed between the first gas inletand the first gas channel.
 13. The apparatus of claim 9, wherein theshowerhead has a plurality of gas passages disposed about the peripheryof a surface of the showerhead adjacent the processing volume, whereinthe plurality of gas passages are fluidly coupled to a purge gas inlet,and wherein the plurality of gas passages are isolated from the firstgas channel, the second gas channel, and the temperature controlchannel.
 14. The apparatus of claim 9, wherein the first gas inlet iscoupled to a metal organic gas source, and wherein the second gas inletis coupled to a nitrogen containing gas source.
 15. The apparatus ofclaim 9, wherein the second gas channel is disposed between the firstgas channel and the temperature control channel.
 16. A method ofprocessing substrates, comprising: introducing a first gas into aprocessing volume of a processing chamber through a first gas inletcoupled to a first gas channel of a showerhead assembly; introducing asecond gas into the processing volume of the processing chamber througha second gas inlet coupled to a second gas channel of the showerheadassembly, wherein the first gas channel is isolated from the second gaschannel, wherein the first gas is delivered into the processing volumethrough a plurality of first plurality of second gas conduits, andwherein at least one of the first gas conduits is concentricallydisposed within at least one of the second gas conduits; and cooling theshowerhead assembly by flowing a heat exchanging fluid through atemperature control channel disposed in the showerhead assembly, whereinthe plurality of first and second gas conduits are disposed through theheat exchanging channel.
 17. The method of claim 16, further comprisingdistributing the first gas across the first gas channel using a blockerplate disposed between the first gas inlet and the first gas channel.18. The method of claim 16, further comprising introducing a purge gasabout the perimeter of the processing volume through a plurality of gaspassages disposed about the periphery of a surface of the showerheadassembly adjacent the processing volume.
 19. The method of claim 16,wherein the first gas is a metal organic precursor and the second gas isa nitrogen containing gas.
 20. The method of claim 19, wherein the metalorganic precursor contains gallium and the nitrogen containing gas isammonia.